The coal seams in the Highveld Coalfield are generally described as flat lying to gently undulating, with a regional dip to the south. The depth of the coal seams increases in a southerly direction. The Highveld coalfield has been affected by numerous dolerite dykes and sills related to the Drakensberg Formation flood basalts. Within the vicinity of the dolerite, the usual structural complications and devolatilization of the coal occurs.

At surface, the soils are described as sandy loams to sandy clay loams. Towards the south, the soil type becomes a dark grey sandy clay, due to the weathering of the underlying dolerite sill. Any outcrops or sub-crops are dominated by sedimentary rocks of the Ecca Group (Vryheid Formation).

The depth of weathering ranges from less than 1.0 m to almost 30 m in a few isolated holes located within the low-lying areas. The weathered zone predominantly comprises a grey-brown sandstone, with minor clay rich intercalations. The impact that the deeply weathered areas may have on the stability of the highwall within the current opencast areas has been reviewed. The resistivity data derived from the Dighem survey was compared to the point data from the drill holes in order to produce a continuous, calibrated surface representing the interface of soft and hard interburden. This surface was included in the geological model to allow a more precise estimation of volumes of the various materials.

In order to model the weath ........

Isibonelo is an opencast colliery using draglines and truck and shovel methods to exploit the coal within the Mining Right; the coal is solely dedicated to the SSF facility. The southern portion of North Pit is too deep for surface extraction and these potential underground resources are being ceded to Sasol for exploitation from the Sasol Syferfontein Shaft. The terms of the supply agreement with Sasol dictate the LoM plan. Isibonelo commenced operations in 2003 where the existing opencast equipment and some portions of the Kriel South resource (owned by the Company at that time) were swapped by the Company in return for an ongoing dedicated supply contract.

This was intended to supply Sasol with 5 Mtpa for at least 20 years (i.e. 100 Mt). This deal was rationalised in 2019 to account for unplanned cost and resource constraints.

The main target coal seam is the No 4 Seam, although the No 5 Seam.

The open pit is designed for dragline operations and in the case of the North Pit the dragline is assisted by a prestrip truck shovel operation. The blocks are designed at 60 m wide by 150 m long.

The mining method in the North Pit is designed to mine a combined total thickness of approximately 65 m which is split into approximately six metres of soft overburden material mined with a hydraulic excavator along with 16 m of hard pre-strip material that is mined with a rope shovel after drilling and blasting. The remainder is mined by the dr ........

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